Elevator safety control system



18, 1964 E. TRESSEL ELEVATOR SAFETY CONTROL SYSTEM 2 Sheets-Sheet 2 Filed Sept. 27 1961 MAIN INVENTOR LAWAfNC'E E TFZ'ISSEL ATTORA/EX Un e S te Pa e 3,144,917 ELEVATOR SAFETY CONTROL SYSTEM Lawrence E. Tressel, 2906 Devereaux St., Philadelphia,

Pa., assignor of fifty percent to Edward Kohlhepp, Philadelphia, Pa.

Filed Sept. 27, 1961, Ser. No. 141,078 4 Claims. (Cl. 187-29) This invention relates generally to an elevator safety control system, and more particularly relates to apparatus for enabling an elevator to be moved to a point where the doors thereof may be opened to release passengers in the event that the elevator becomes stopped between floors due to an electrical failure somewhere in the power or control system, this application being a continuation-inpart of my co-pending application, Serial No. 63,415, filed October 18, 1960.

The electrical failure can, of course, be of two kinds, one in which for example electrical service is interrupted as a result of some condition external to the electrical system of the particular elevator affected, and the other type of failure being one which occurs due to a malfunctioning of some portion of the electrical system specifically associated with a particular elevator. Regardless of the source of the difiiculty, the end result in either instance is that electrical power for a given elevator is interrupted and the car is brought to a halt at some unpredictable point. In general, the probability is high that the final stopped position of the elevator will be such that the elevator doors cannot be safely opened, or opened at all, to release the passengers then being carried within the elevator. In some cases, a panic may develop amongst the passengers with the attendant possibility of serious injury to some. At the very least, the enforced confinement of a number of passengers within the very restricted confines of the elevator results in severe annoyance. Accordingly, it is a primary object of this invention to provide apparatus effective to move a stalled elevator from its stopped position to some point at which the passengers may be quickly and safely evacuated from the disabled elevator car.

Another object of this invention is to provide a novel apparatus for moving a stalled elevator car as aforesaid under the control of a person external to the elevator.

Yet another object of this invention is to provide novel elevator control apparatus for moving a stalled elevator to a passenger releasing station wherein the control apparatus is interlocked with the main electrical system in such manner as to be automatically rendered operable upon the occurrence of a power failure and to be automatically rendered inoperable upon the restoration of normal power to the system.

A further object of the invention is to provide novel apparatus for moving a stalled elevator to a desired location by the provision of control devices easily connected into the power system of existing elevator drives.

The foregoing and other objects of the invention will become apparent from a reading of the following specification in conjunction with an examination of the appended drawings, wherein:

FIGURE 1 is a diagrammatic representation of a counterweight and cable type of elevator system and shows an elevator in a stopped position between two floors;

FIGURE 2 illustrates a typical overhead motor drive for operating the cable system of an elevator of the type shown in FIGURE 1, a solenoid operated brake system for preventing elevator motion and for freeing the elevator for travel under the control of the motor, and a part of the control device according to the invention;

FIGURE 3 is a block diagram representation of the elevator control system according to the invention by 3,144,917. Patented Aug. 18, .1964

ice

means of which emergency raising or lowering of the elevator car under the control of a person external to the elevator may be effected;

FIGURE 4 is a schematic diagram of the control apparatus according to the invention in a circuit connection with a portion of the normal elevator electrical circuitry;

and

FIGURES 5, 6 and 7 illustrate several modifications of the control circuitry of the invention.

In the several figures, like elements are denoted by like reference characters.

Turning first to an examination of FIGURE 1, there will be seen a building designated generally as 10, having a plurality of floors 11 each of which opens through a doorway 12 to a common elevator shaft 13. Disposed Within the elevator shaft 13 for vertical motion from floor to floor is an elevator car 14 suspended from above by means of the support cables 15 and 16 and the counterweight 17. Also disposed within the elevator shaft 13 and extending vertically upward and downward therethrough is a cable 9 which moves in accordance with the motion of the elevator, so that visible indicators may be associated therewith to provide a means for determining the position of the elevator from an external control station at any time. The already existing elevator governor cable may be utilized for this purpose, or any other suitable position indicator may be used, the particular form of indicator being immaterial to the invention.

Additionally, a travelling electrical cable 19 extends between the elevator car 14 and an electrical supply source 18, the latter being representationally shown merely as a box-like affair. The electrical supply 18 may in fact be a wiring box through which external circuits are connected to the travelling electrical cable 19, which latter includes a number of conductors for effecting control of various devices from the elevator car 14 such as the car lights, ventilating fan, telephone circuits, and the operating controls for producing door opening and closing and other car motion. Included among the circuits of the travelling cable 19 is a circuit comprising the coil of the brake drum solenoid 25, which will be referred to in connection with the showings of FIGURES 2 through 7.

The elevator support cables 15 and 16 extend upward into what is known as a penthouse where these cables are wrapped about a pair of sheaves driven by a motor and by means of which the elevator is raised and lowered. Such an arrangement is illustrated in the showing of FIG- URE 2 where it will be observed that the penthouse floor 20 supports thereabove a motor and a first sheave designated generally as 21, and carries therebelow the second- 7 ary sheave designated generally as 22. The support cables 15 and 16, which in actuality are a single continuous cable, extend upward from the counter-weight and elevator car 14 and are wrapped about the first and secondary sheaves. The driving motor, being electrically reversible under the control of the elevator operator, drives the sheaves in one sense or in the opposite sense to cause the elevator car 14 to be raised or lowered.

Integrally secured to the motor and first sheave 21 for rotation therewith is a brake drum 23 which is frictionally engaged with and disengaged from a pair of brake shoes 24 under the control of an electrically actuated solenoid 25. The mechanics of the brake systems are conventional and are arranged in a fail-safe type of system so that deenergization of the solenoid 25 results in engagement of i the brake drum 23 by the brake shoes 24 under the urging of the heavy compression springs 26. Thus, when the solenoid 25 is deenergized the brake is engaged and the car is held motionless. Deenergization of the solenoid 25, of course, normally occurs under the control of the elevator operator when it is desired to stop the car at a floor.

-However, deenergization of this solenoid 25 can also occur due to malfunctioning of the control equipment, opening of the solenoid winding, or loss of primary electrical power. When any of these contingencies occur it is, of course, desirable that the elevator be locked in position in order to prevent a runaway condition of the elevator car which could cause serious injury or possibly even death to the occupants of the car should the elevator suddenly plummet down through the elevator shaft. For this reason these brake systems are normally set-up in the failsafe fashion so that loss of control of the elevator causes the brake to be engaged immediately.

There are, of course, certain disadvantages to this type of arrangement because the loss of elevator car control does not always occur when the car is at a convenient position for discharging any passengers that are at the time being transported. Unfortunately, experience seems to indicate that service outages occur when the elevator car is at some transition point between floors. The instant invention provides an auxiliary control system whereby when such an undesired occurrance takes place, control the brake solenoid 25 is obtainable by service personnel external to the elevator car and the brake may be released and reapplied in a controlled manner to move the elevator to a point where it is in alignment with one of the doorways 12 at a conveniently located floor 11 so that the elevator doors may be opened and the passengers discharged. A typical auxiliary control system by means of which such control may be exercised over the brake system by persons external to the elevator car is illustrated in FIGURES 3 and 4, and, as will be seen, is connected into the brake solenoid electrical system through the solenoid electrical energizing conductors 27 which also control the operation of the solenoid during normal operation of the elevator system.

As seen in the diagrammatic showing of FIGURE 3, and partially in FIGURE 2, the shaft 21a of the cable sheave 21 has fitted upon its end for simultaneous rotation therewith a pulley 52. The pulley 52 is coupled by means of the drive belt 53 to a second pulley 54, which latter is in turn coupled to one half of a magnetic clutch 55 via a connecting shaft 56. The pulleys 52 and 54 could of course also be sprockets, in which case the belt 53 would be a sprocket chain. The other half of the magnetic clutch 55 is coupled via the shaft 57 to a motor speed reducer 58, which latter is coupled to a reversible auxiliary electric motor 59 via the shaft 60. The auxiliary motor 59 is energizable and deenergizable through the agency of control cirucits 65 to which the motor is connected by conductors 61 to 64. The control circuits are fed from the terminals 39 of a source of auxiliary electrical power via the conductors 43, 47, 51 and 51b, and the magnetic clutch is electrically energizable from the auxiliary power source through conductor 51a and through the control circuits 65 via conductor 66. The brake solenoid 25 while normally fed from the main power source through conductors 33 and 35, is seen to be also electrically connected to the auxiliary power source terminals 39 through the control circuits 65 and conductors 41 and 50.

When the elevator system is operating in normal fashion, the auxiliary motor 59, magnetic clutch 55 and auxiliary power source terminals 39 are deenergized, the two halves of the clutch 55 are decoupled; the pulleys 52 and 54 rotate in accordance with the rotation of the sheave 21 as controlled by the operator controlled elevator main drive motor; and the brake solenoid 25 is actuated by the elevator operator through the normal car circuits. However, in the event of a power failure in the main electrical system, the control circuits 65 disconnect the brake solenoid 25 from the main power circuits and connect it to the auxiliary power circuit through the terminals 39 by means not shown in FIGURE 3 but which are illustrated in FIGURE 4 to be described, and also cause energization of the auxiliary power source terminals 39. By

means of the control circuits 65 the brake solenoid 25 may now be energized either with or without attendant energization of the auxiliary motor 59 and magnetic clutch 53.

Actuation of the brake solenoid 25 alone permits only gravity to operate on the mass system of the elevator car and counterweight, so that if a sufficient mass unbalance exists to overcome the static friction of the entire mechanical system the elevator car will ascend or descend in accordance with the sense of the mass unbalance. That is, if the car and its load is heavier than the counterweight, the car will descend, and vice-versa.

There exist, however, three circumstances in which gravity operation is of no use whatever. Firstly, in the case where there does not exist sufiicient mass unbalance to overcome the static friction of the entire mechanical system, then actuation of the solenoid 25 while releasing the brake will not result in any car motion. Secondly, if a heavily loaded car were to have overshot the bottom floor while moving downward, release of the brake would cause the car to descend into the elevator pit and probably worsen the situation. Finally, if a lightly loaded car were to have overshot the top floor while moving upward, release of the brake would cause the car to ascend toward the penthouse and again worsen the situation.

In these three cases it is necessary either to assist gravity or to overcome gravity, and for these purposes the auxiliary power drive provided by the auxiliary motor 59 may be brought into operation. By means of the control circuits the magnetic clutch 55 may be energized to thereby couple the auxiliary motor 59 to the shaft 21a of the cable sheave 21 through the belt and pulley system. The motor 59 may now be selectively energized for rotation in either direction as dictated by the particular circumstances of the elevator car position, and may be thereafter deenergized and the brake re-applied when the car has been moved to the desired point in the elevator shaft. Consider now the electrical system of FIGURE 4.

In the circuit of FIGURE 4, main electrical power is supplied to a pair of terminals 28 and flows therefrom through a pair of conductors 29 to the poles and contacts 30 of a relay 31, which relay is part of the control system circuits 65. The circuit is completed through the traveling cable 19, conductors 32 and 33, elevator car switch 34, brake solenoid 25 and its associated conductors 27, and conductor 35. Normally, when the switch 34 in the elevator car 14 is closed by the elevator operator a closed electrical circuit is completed through the brake solenoid 25 which energizes the solenoid and releases the brake shoes 24 from engagement with the brake drum 23 to allow the elevator car 14 to be moved up or down by means of the conventional motor drive system located in the penthouse. The electrical circuit just traced will normally also include interlocks and other devices, which are not shown, and when any one of these devices fails the circuit is interrupted and renders the switch 34 in the elevator car 14 inoperative for energizing of the solenoid 25 so that the car may not be moved.

In this regard it should be borne in mind that the main power terminals 28 are not necessarily intended to be considered as being connected directly to a power source such as an incoming power line or a generating system, but are in fact intended to be connected outward through the rest of the elevator control system and ultimately to a power source so that the various interlocks and other controls associated with the circuit should be considered as existing at some other point in the system to which the terminals 28 are connected. Therefore, failure of any one of these components or of the main power source itself will result in a loss of power at the conductors 29. The conductors 29 therefore represent a convenient point in the system for sensing the condition of the electrical system. Relay 31, and hence the poles and contacts 30 of that relay form part of the auxiliary control system 65 to be described, and in the absence of such an auxiliary control system the conductors 29 would not pass through the poles and contacts 30 of the relay 31 but would instead be connected directly to the conductors 32 and 35.

The relay 31 includes a pair of relay actuating windings 36 electrically connected in parallel across the conductors 29 and are normally energized therefrom, each of the windings 36 being capable of actuating the poles and contacts of the relay 31 even under the condition where one of the windings fails. Each winding 36 has coupled thereto a sensing winding 37 which provides a stepped down voltage for energizing the pilot bulbs 38. Thus, when current flows through both of the windings 36, the pilot bulbs 38 will be illuminated and will indicate a normal operating condition. If either winding should fail, as for example by becoming open circuited, then the pilot bulb associated with that winding will be extinguished since the absence of current flow through the open winding will interrupt the transformer action to the sensing winding 37. In such a case, the service personnel will notice that a particular bulb has been extinguished, and after first replacing the bulb to insure that the bulb itself has not burned out, it will be known that one of the windings has failed and it may then be replaced. The probability of both windings 36 becoming, simultaneously open circuited is quite remote, and when therefore the service personnel should note that both pilot bulbs have been extinguished it will be fairly well certain that the trouble in the system has occurred beyond the terminals 28 at some point not illustrated in the diagram.

It addition to the poles and contacts 30 of the relay 31 there is provided a second set of poles and contacts 39 and an auxiliary pole and contact 40, all commonly actuated by the relay windings 36. In the illustrated condition, the relay windings 36 are energized and have caused the relay poles 30 to close with their associated contacts While simultaneously causing the relay poles 39 and 40 to disengage from their associated contacts. Should the conductor lines 29 be deenergized due to a loss of power at some point in the system, the relay actuating windings 36 will, of course, become deenergized and the poles 36 will disengage from their associated contacts while the poles 39 and 40 close into engagement with their contacts. In this condition the brake solenoid 25 is disconnected from the main circuit and is now placed in the auxiliary control system. The portion of the auxiliary control system which permits the brake solenoid 25 to be selectively operated from a control station may be traced in a closed loop from the brake solenoid conductor 27 at the lower end of the solenoid 25 over to the right through a conductor 41, through a normally open switch 42, conductor 43 to the right-hand pole and contact 39 and therethrough to a conductor 44 and one of a pair of auxiliary terminals 45. From the other auxiliary terminal 45 the circuit follows to the left through a conductor 46, through the left-hand relay pole and contact 39 to a conductor 47, which latter connects to the remaining brake solenoid conductor 27 through conductor 50.

The auxiliary terminals 45 are coupled to a source of auxiliary electrical energy, which may be a normal house line circuit or which may be a motor-generator set. In the event that the auxiliary power source is a motor-generator set, then the pole and contact 40 of the relay 31 will be utilized, otherwise not. Since an emergency motor-generator set is not normally operating, some means are required to start up the generator when power is required to be delivered therefrom. This may conveniently be accomplished by the auxiliary pole and contact 40 which will, of course, close when the relay 31 becomes deenergized. The pair of conductors 48 leading from the auxiliary contact 40 complete a circuit through the starter mechanism of the motor-generator set to cause automatic start up of the generator when the relay 31 becomes deenergized, and also causing automatic stopping when normal service is resumed and the relay 31 is again energized from the conductor line 29.

The switch 42 would be located at some convenient station such as on the top floor or at the bottom 11001" of the building in which the stalled elevator is located so that the service personnel may proceed to the switch station, depress the switch 42 to complete the circuit from the auxiliary power source through the brake solenoid 25, and thereby release the brake. The elevator car 14 will usually then move under the influence of gravity either up or down depending upon the mass relationship between the counterweight 17 and the elevator car 14 together with its passenger load. Any convenient means, such as the indicator cable 9, for indicating the position of the elevator at a given time may be employed so that the service personnel operating the switch 42 can determine precisely when the elevator comes into apposition with the doorway 12 of a desired floor 11, whereupon the switch 42 would be released and the elevator stopped for the release of the passengers.

In the three cases previously mentioned where release of the brake results in either no elevator car motion or motion in the wrong direction, the auxiliary power drive system must be brought into operation. As set forth in the description of FIGURE 3, this auxiliary power drive includes the reversible motor 59 and the magnetic clutch 55. In FIGURE 4, the motor 59 is shown as having an armature 59a and a field winding 59b, the armature 59a being reversibly electrically series connected with the field 5% by means of the conductors 61, 62 and 63, and the poles 70, 72 and contacts 71, 71a, 73, 73a of the relay 68. Transfer of the relay poles 70, 72 from one set of contacts 71, 73 to the other set of contacts 71a, 73a to eifect motor reversal is achieved by energization of the relay winding 67 through the agency of the centeropen double-pole double-throw switch when the poles 77 and 78 or" the latter are thrown to the right to respectively engage their associated contacts 74 and 76, the relay winding 67 being then energized from the auxiliary power source conductors 47, 43 through conductors 51, 51b, 69, 41 and switches 42 and 75.

With the relay winding 67 thus energized the motor 59 is energized to raise the elevator, current flow through the motor being traceable from the conductor 51a through the relay pole 70 and contact 71a, conductor 62, armature 59a, a conductor 61 to relay contact 73a and pole 72, thence over conductor 63 and through the field winding 5% to conductor 64 which connects to contacts 76 and 76a of switch 75, through switch 75, pole 78 to conductor 41 and then through switch 42. When switch 75 is either in its center-open position, as shown, or is thrown to the left so that the poles 77 and 78 respectively engage the contacts 74a and 7611, the winding 67 of relay 68 is deenergized and the relay poles 70 and 72 engage the contacts 71 and 73 as shown. In the illustrated center-open position of switch 75 the motor 59 is deenergized and the power drive is inoperative. However, with the switch 75 thrown to the left the motor 59 is energized to lower the elevator, current flow through the motor being trace able as before except for the fact that the current flow through the armature 59a is reversed due to the changed positions of the relay poles 70 and 72 since the relay winding 67 is deenergized. The winding 55a of the magnetic clutch 55 is seen to be connected in parallel with the motor circuit by conductors 51a and 66 so that the magnetic clutch is actuated by switch 75 whenever the motor 59 is energized and irrespective of the direction of motor rotation.

Since the auxiliary power drive circuits are all returned to the auxiliary power source through the switch 42, it will be understood that the power drive can not be activated while the brake is applied because closure of switch 42 energizes the brake solenoid 25 and non-closure of switch 42 prevents energization of the power drive.

Therefore, FIGURE 4 illustrates an organization which permits either gravity operation or power drive operation. Gravity operation alone is carried out by closing of switch 42, and power drive operation is accomplished by throwing switch 75 to the right or left in conjunction with the closing of switch 42. Both switch 42 and 75 may be of the spring return type so that neither switch may be inadvertently left in a closed condition.

In this regard it will be observed that should switch 75 remain closed when the main power is restored, the power drive circuits would be energized from the main power source whenever the switch 34 in the elevator 14 were to be closed. This is an obviously undesirable condition since the main drive and auxiliary power drive would then be simultaneously in operation and could even be driving in opposition to one another. The switch '75, spring return feature avoids this situation. However, as an additional precaution it may be desired to incorporate an automatic disconnect into the circuit. Such a disconnect is illustrated in FIGURE 4 by the dashed line pole and contact connected in series with the conductor line 41. This pole and contact $6 would be opened and closed by actuation of relay 31 at the same time as the poles and contacts 39 are opened and closed, so that when the main power circuit is connected to the brake solenoid 25 the pole and contact 86 are open and the condition of switch 75 is rendered immaterial.

FIGURE 5 illustrates a modification of FIGURE 4 in that the conductor line 41 of FIGURE 4 has been disconnected from the poles of switch 75 and connected to conductor 66, and switch 42 has been eliminated by connecting conductor 43 to the poles of switch 75. The shift of conductor 41 is necessitated by the fact that control of the brake solenoid 25 must be maintained at all times. Since switch 42 has been eliminated, the brake solenoid circuit must be returned through switch 75 in order to avoil immediate release of the brake upon the application of auxiliary power. This circuit provides for power drive operation only since the clutch and motor circuits are energized whenever switch 7 5 is thrown and hence whenever the brake solenoid 25 is energized.

FIGURE 6 illustrates a modification of the circuit of FIGURE 4 in that the relay 6% and switch '75 of FIGURE 4 have been replaced by a center-open triple-pole doublethrow switch 79 having poles 80, 81, 82 and contacts 83, 83a, 84, 84a, 85, 85a. The pole 82 and associated contacts 85, 85a are organized in the circuit of FIGURE 6 in exactly the same manner as the pole 78 and contacts 76, 76a of switch 75 are organized in the circuit of FIGURE 4. The poles 80 and 81 together with their associated contacts replace the poles and contacts of the relay 6% of FIGURE 4, the sole difference being the center-open position of the poles 80 and 81. Operation of the circuits of FIGURES 4 and 6 is the same excepting that in FIGURE 6 the power conductors 51b, 61, 62, 63 and 64 must be run to the location of switch 79, whereas in FIGURE 4 only the conductors 69 and 64 must be so run and conductor 69 merely carries the relay winding current.

FIGURE 7 bears the same relationship to FIGURE 6 as FIGURE 5 bears to FIGURE 4. That is, FIGURE 7 differs from FIGURE 6 in that switch 42 has been eliminated and conductor 41 has been disconnected from pole 82 of switch 79 and connected to conductor 66, and hence FIGURE 7 provides for single switch controlled power drive operation only.

It will be appreciated that in the circuits of FIGURES 4 and 5 the power conductor 64 could if desired be returned directly to conductor 43 through the pole and contact of an additional relay (not shown) whose winding could be energized by pole 78 and contacts 76, 76a of switch 75. In this case the power circuits could be confined to the pent house.

Upon the return to normal service resulting in the reenergization of the conductor lines 29, the relay actuating windings 36 will again become energized to transfer the another and cause abnormal system conditions, which could readily occur if the main and auxiliary power systems supplied alternating current. It should be noted that the auxiliary control system 65 for actuating the brake solenoid 25, auxiliary motor 59 and clutch 55 bypasses the switch 34 located in the elevator car 14, so that control of the brake system and auxiliary power drive lies exclusively with the service personnel that operate the control switch 42. An auxiliary switch 49 is shown in dashed line as being placed in parallel with the switch 42, and the switch 49 represents one or more additional switches which may be located at a plurality of diiferent convenient locations so that the brake solenoid control portion of the auxiliary control system may be operated from various stations if desired. Similarly so located may be other switches 75 or 79 for controlling the auxiliary power drive.

It should be noted that the switch 34 in the elevator car 14 has been illustrated in FIGURE 4 only in order to clearly show the transfer of control from this switch to the auxiliary power circuit. In practice, the conductors 32 and 33 may be connected together and the switch 34, may then be located with the other elevator control circuits which are not shown, so that a malfunction of this switch would also cause operation of the relay 31. In FIGURE 4 for example, the switch 34 could be series connected into either conductor 29 immediately adjacent to one of the terminals 28.

In some systems, the described apparatus would cause transfer to the auxiliary power system whenever the switch 34 or some interlock were opened during normal use, as for example when opening the elevator doors. Of course, upon the closing of the interlocks the relay 31 would retransfer to the main power system. Thus, the relay 31 would be normally in operation and would tend to avoid hang-up malfunctioning due to too little use. Gptionally, the relay 31 function might be dispensed with so that the conductors 29 would be tied directly to the conductors 32 and 35 while the conductors 43 and 47 would be connected respectively to the conductors 44 and 46. This latter arrangement, of course, does away with the isolation between the main and auxiliary power supplies which is provided by the relay. Finally, it should be realized that a relay 31 failure still permits the elevator car to be moved since a relay drop-out resulting from simultaneous opening of both windings 36 or short circuiting of at least one winding will merely result in bringing the auxiliary power circuit into operation.

Having now described my invention in connection with particular illustrated emboliments thereof, it will be appreciated that variations and modifications will naturally occur from time to time to those persons normally skilled in the art without departing from the essential scope or spirit of my invention, and accordingly, it is intended to claim the same broadly as Well as specifically as indicated by the appended claims.

What is claimed as new and useful is:

1. Auxiliary control apparatus operable from a control station external to an elevator for selectively causing the elevator to move to a desired position in the elevator shaft comprising in combination, normally inoperable first auxiliary electric circuit means coupled to the normal elevator position holding device for selectively actuating and deactuating the latter, an electrically energizable auxiliary power drive including an electrically reversible motor and a clutch mechanism for coupling the motor to the mechanical hoist of the elevator, said auxiliary power drive being operable when energized to move the elevator to the desired position in the elevator shaft, normally inoperable second auxiliary electric circuit means coupled to said auxiliary power drive for selectively energizing and deenergizing the latter, said second auxiliary electric circuit means including a selectively operable switch in electric circuit connection with said motor effective when operated in one way to cause motor armature rotation in one sense and when operated in another way to cause motor armature rotation in the opposite sense, and means automatically operating when the elevator main power drive is disabled to prevent control of the elevator motion from the interior of the elevator while simultaneously rendering operable said first and second auxiliary electric circuit means.

2. The auxiliary control apparatus as defined in claim 1 wherein said clutch mechanism is electrically actuated and deactuated by said selectively operable switch, said clutch being actuated to couple said motor to the elevator hoist mechanism when said motor is energized by said switch and being deactuated to decouple said motor from the elevator hoist mechanism when said motor is deenergized by said switch.

3. The auxiliary control apparatus as defined in claim 1 wherein said normal elevator position holding device is an electrically actuated device, wherein said first auxiliary electric circuit means for selectively actuating and deactuating said elevator position holding device comprises a selectively operable switch in electric circuit connection with said holding device, and wherein the selectively operable switches of said first and second auxiliary electric circuit means are intercoupled so that said auxiliary power drive is rendered operable only when said elevator position holding device is actuated to release the elevator for movement.

4. The auxiliary control apparatus as defined in claim 3 wherein the intercoupling between the selectively operable switches of said first and second auxiliary electric circuit means is a series electric circuit intercoupling so arranged that energizing current flow through the auxiliary power drive motor must flow in series through both of said switches.

References Cited in the tile of this patent UNITED STATES PATENTS 2,701,033 Chiselbrook Feb. 1, 1955 

1. AUXILIARY CONTROL APPARATUS OPERABLE FROM A CONTROL STATION EXTERNAL TO AN ELEVATOR FOR SELECTIVELY CAUSING THE ELEVATOR TO MOVE TO A DESIRED POSITION IN THE ELEVATOR SHAFT COMPRISING IN COMBINATION, NORMALLY INOPERABLE FIRST AUXILIARY ELECTRIC CIRCUIT MEANS COUPLED TO THE NORMAL ELEVATOR POSITION HOLDING DEVICE FOR SELECTIVELY ACTUATING AND DEACTUATING THE LATTER, AN ELECTRICALLY ENERGIZABLE AUXILIARY POWER DRIVE INCLUDING AN ELETRICALLY REVERSIBLE MOTOR AND A CLUTCH MECHANISM FOR COUPLING THE MOTOR TO THE MECHANICAL HOIST OF THE ELEVATOR, SAID AUXILIARY POWER DRIVE BEING OPERABLE WHEN ENERGIZED TO MOVE THE ELEVATOR TO THE DESIRED POSITION IN THE ELEVATOR SHAFT, NORMALLY INOPERABLE SECOND AUXILIARY ELECTRIC CIRCUIT MEANS COUPLED TO SAID AUXILIARY POWER DRIVE FOR SELECTIVELY ENERGIZING AND DEENERGIZING THE LATTER, SAID SECOND AUXILIARY ELECTRIC CIRCUIT MEANS INCLUDING A SELECTIVELY OPERABLE SWITCH IN ELECTRIC CIRCUIT CONNECTION WITH SAID MOTOR EFFECTIVE WHEN OPERATED IN ONE WAY TO CAUSE MOTOR ARMATURE ROTATION IN ONE SENSE AND WHEN OPERATED IN ANOTHER WAY TO CAUSE MOTOR ARMATURE ROTATION IN THE OPPOSITE SENSE, AND MEANS AUTOMATICALLY OPERATING WHEN THE ELEVATOR MAIN POWER DRIVE IS DISABLED TO PREVENT CONTROL OF THE ELEVATOR MOTION FROM THE INTERIOR OF THE ELEVATOR WHILE SIMULTANEOUSLY RENDERING OPERABLE SAID FIRST AND SECOND AUXILIARY ELECTRIC CIRCUIT MEANS. 